Dogs pick up directions from human voices

May 6, 2014
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A woman holds a piece of dog food, which she'll place in one of the two black boxes while the red curtain keeps the dog from seeing which box she's putting it in. / Max Planck Institute for Evolutionary Anthropology

by Traci Watson, Special for USA TODAY

by Traci Watson, Special for USA TODAY

When every call of "Spot, come!" sends your dog running in the opposite direction, it's easy to be cynical about how well canines listen. But a new study shows dogs and even puppies are capable of understanding subtle and indirect cues in human voices, a finding with implications for how dogs came to be deeply attuned to human behavior.

The study found that dogs of all shapes and sizes could home in on a treat based entirely on the direction in which a hidden human was speaking. Human babies can do the same, but our clever cousins the chimpanzees can't, according to a 2012 study.

"The message of this study is not that chimps are stupid and dogs are smart," says lead study author Federico Rossano of Germany's Max Planck Institute for Evolutionary Anthropology. "What it tells us is that dogs pay special attention to communicative signals from humans. ‚?¶ That's a sign of how connected we are."

The new findings are "fascinating," says Evan MacLean of Duke University's Canine Cognition Center but also "surprising ‚?¶ because it's a very subtle cue. When I was reading the paper, I was wondering, 'Gosh, can I do this?' " Scientists have long known that dogs are extraordinarily sensitive to visually based social cues from humans, but this is the first evidence they're sensitive to auditory cues, MacLean says.

Rossano and his colleagues had two criteria for their experimental subjects: They had to be comfortable being left with strangers, and they had to be food-motivated. Dogs ranging from Jack Russell terriers to German shepherds watched as an experimenter held up a piece of kibble and said, "Pay attention!" The experimenter ducked behind a barrier, surreptitiously placed the food in one of two black boxes and moved the boxes so the dog could see them.

Then came the crucial test. The hidden experimenter sat close to the empty box but faced the box holding the food and called, "Oh look, look there, this is great!" Instead of heading for the box close to the source of the voice, the dogs trotted over to the food-laden box the experimenter was speaking toward. So the animals seemed to understand that the human was talking about one of the boxes, rather than summoning the dog to the food, and the dogs interpreted the direction of speech to figure out the location of the box with the treat.

Adult dogs did well at this task, but puppies only 8 to 14 weeks old did even better ‚?? if they had spent plenty of time with people. Puppies that had lived mostly with their litter mates, on the other hand, flubbed the test. These results show that dogs need some kind of learning ‚?? perhaps in the form of socialization with people - to pick up the clues embedded in a human voice, Rossano says. The ability of such young dogs to do so well suggests dogs have a genetic predisposition to focus on humans and the signals they convey, the researchers say in this week's issue of the Proceedings of the Royal Society B: Biological Sciences.

"In the debate that says, 'It's all about socialization' or 'It's all about genetics,' the answer, as always, is somewhere in the middle," Rossano says.

The results support the idea that socialization is key, agrees cognitive psychologist Monique Udell of Oregon State University. But she says she doesn't think the study helps confirm that dogs are genetically tuned to follow every twitch of the human face, every syllable of human speech. Perhaps dogs are simply superior at reading communicative cues of all kinds, not just those of humans, Udell says.

It's possible that the dogs just made a beeline for the box where the sound was loudest, says √Ād√°m Mikl√≥si, head of the Family Dog Project at Hungary's E√∂tv√∂s Lor√°nd University. Rossano responds that from the dogs' vantage point, the volume of sound barely differed from one end of the barrier to the other, and it's unlikely the dogs would immediately learn to associate a louder sound with food. He says he thinks the canines use other clues encoded in the sound to figure out where the speaker directs her words. That orientation acts like a finger pointing to the food.

"The take-home message (is) there's a lot of information dogs can pick up when they're in the presence of humans," Rossano says. "We should care for them and be attentive and also be amazed by how special they are in picking up all these signals and how much they care about us."